[NO-ISSUE][LANG] Small tweaks for language extensions

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
- Weakening visibility for mergeScope in scoping visitor.
- Allowing children of SQL++ function call resolver.

Change-Id: Ib83addfaca52cf63b4ef658b61547e05164ab5bc
Reviewed-on: https://asterix-gerrit.ics.uci.edu/c/asterixdb/+/17733
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Glenn Galvizo <ggalvizo@uci.edu>
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppFunctionCallResolverVisitor.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppFunctionCallResolverVisitor.java
index 38b66e2..2ded389 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppFunctionCallResolverVisitor.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/rewrites/visitor/SqlppFunctionCallResolverVisitor.java
@@ -33,7 +33,7 @@
 import org.apache.asterix.lang.sqlpp.visitor.base.AbstractSqlppSimpleExpressionVisitor;
 import org.apache.asterix.om.functions.BuiltinFunctions;
 
-public final class SqlppFunctionCallResolverVisitor extends AbstractSqlppSimpleExpressionVisitor {
+public class SqlppFunctionCallResolverVisitor extends AbstractSqlppSimpleExpressionVisitor {
 
     private final LangRewritingContext context;
 
diff --git a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/base/AbstractSqlppExpressionScopingVisitor.java b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/base/AbstractSqlppExpressionScopingVisitor.java
index 765c2be..dd48680 100644
--- a/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/base/AbstractSqlppExpressionScopingVisitor.java
+++ b/asterixdb/asterix-lang-sqlpp/src/main/java/org/apache/asterix/lang/sqlpp/visitor/base/AbstractSqlppExpressionScopingVisitor.java
@@ -437,7 +437,7 @@
     }
 
     // Merges <code>scopeToBeMerged</code> into <code>hostScope</code>.
-    private void mergeScopes(Scope hostScope, Scope scopeToBeMerged, SourceLocation sourceLoc)
+    protected void mergeScopes(Scope hostScope, Scope scopeToBeMerged, SourceLocation sourceLoc)
             throws CompilationException {
         Set<String> symbolsToBeMerged = scopeToBeMerged.getLocalSymbols();
         for (String symbolToBeMerged : symbolsToBeMerged) {